Field of the Invention
The present invention relates to a wireless power transfer technique.
Description of the Related Art
Recently, there have been available a wireless power transfer technique of wirelessly transferring power and a contactless charging technique. Studies have been made to make a power transmitting apparatus on the power transmission side perform power transmission control in accordance with the state of a power receiving apparatus on the power reception side when performing wireless power transfer (Japanese Patent Laid-Open Nos. 2006-197734 and 2006-340541). Japanese Patent Laid-Open No. 2006-197734 discloses that an apparatus, which transmits power while transmitting data, monitors data to be transmitted and increases the amount of power to be transmitted, for example, in the intervals between songs. In addition, Japanese Patent Laid-Open No. 2006-340541 discloses that a power feeding apparatus on the road side receives vehicle information about a vehicle as a power receiving apparatus and controls transmitted power based on the vehicle information.
However, the techniques disclosed in Japanese Patent Laid-Open Nos. 2006-197734 and 2006-340541 do not consider anything about power demand in the power receiving apparatus, and hence cannot transmit power in synchronization with a change in power demand in the power receiving apparatus.